[Cialug] REALLY weird problem

[Todd E Thomas]

Even if the Ethernet cards are loose they should either work or not work.
I've not observed any in-between behavior. Of course I always allow for the
x factor.

Ruling a few factors in/out:
Assuming a server, the configuration is written by you, the admin - and not
managed by Network Manager / DHCP, the system shouldn't be writing that
file and therefore lose information during a power outage: the
configuration should be fine in most cases. If not:
# mv eth0 > eth0_old
# cat eth0_old > eth0

Restart networking, retest.

>From an OS perspective, perhaps the driver has become boogered during the
power failure; it might be time to reinstall the driver
<http://computernetworkingnotes.com/network-administrations/how-to-install-lan-card-driver-in-linux-location-of-networking-files-and-descriptions.html>.
This should almost never happen.
---

The easiest solution is to replace the cards and retest. The hardware
monitor should see the new cards on reboot and load the correct drivers.

If they behave:
*The Same*: the board may have received power spike damage.
*As Expected*: the old cards may have received power spike damage. You're
in and our for about $60-80.

If the not knowing keeps you up at night (as it would me), verify the old
cards. Put them back in the server then install Wireshark and/or tcpdump on
the system and monitor the cards individually. Try to connect to them again
under the same conditions, then stop whichever monitoring program you've
used.

Afterwards check the logs for dropped packets. One of two (probable)
outcomes will present itself:

   1. The old cards behave as expected; perhaps factor x (they weren't
   seated as they should have been) but *you're done*. Put the other cards
   on the shelf; you should have replacements laying around anyway.
   2. The problem persists; replace the old cards with the new, then toss
   the old cards and move on with life.

There are too many other (improbable) outcomes to list. I bet this gets you
where you need to be.

--
Thanks in advance,

Todd E Thomas
C: 515.778.6913

*"It's a frail music knits the world together."-Robert Dana*


On Thu, Feb 19, 2015 at 2:34 PM, L. V. Lammert <lvl at omnitec.net> wrote:

> On Thu, 19 Feb 2015 j.bengtson at mchsi.com wrote:
>
> > Is it possible that one or more of the cards have worked a little loose?
> >
> There are on the MB, .. so I don't think so.
>
>         Thanks!
>
>         Lee
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